This is general guidance based on standard permitted development rights in England. Rules differ for listed buildings, conservation areas, and properties with Article 4 directions. Always confirm with your local planning authority before starting work.
Do I Need Planning Permission for a Loft Conversion with Roof Lights Only in Westminster?
A loft conversion that uses roof lights (such as Velux windows) rather than dormers. Because no additional roof volume is added, this type is subject to fewer planning restrictions, though Building Regulations still apply.
Planning in Westminster
86%
of planning applications granted
81%
decided within the statutory or agreed time
53%
of householder applications decided within 8 weeks
In the year to December 2025, Westminster decided 4,828 planning applications. 435 of these were householder projects such as extensions, loft conversions and outbuildings, of which 79% were granted.
Planning statistics: MHCLG planning application statistics, the year to December 2025. Conservation area and Article 4 data: planning.data.gov.uk, © Historic England / Crown copyright. Open Government Licence v3.0.
Important: Additional Restrictions May Apply in Westminster
Westminster has 56 conservation areas. These include Adelphi, Albert Gate, Aldridge Road Villas And Leamington Road Villas, Bayswater, Belgravia, Birdcage Walk. If your property is in a conservation area, some or all permitted development rights may be restricted. For example, you may need planning permission for changes that would normally be permitted, including alterations to the roof, cladding, or extensions visible from a public highway.
Westminster has 10 recorded Article 4 directions. These include Queens Park Estate. Article 4 directions remove specific permitted development rights in defined areas. If your property is covered by an Article 4 direction, you may need planning permission for work that would normally be permitted. Contact Westminster planning department to check whether an Article 4 direction applies to your property.
Check with Westminster planning department before starting work to confirm whether your property is affected by any special designations.
Permitted Development Rules for a Loft Conversion with Roof Lights Only
Generally permitted as the addition of roof lights does not increase the volume of the roof space. Roof lights to the rear are permitted development. Side-facing roof lights at upper floor level must be obscure glazed and non-opening below 1.7m from the floor.
Conditions
- 1Roof lights must not protrude more than 150mm beyond the plane of the roof slope
- 2Side-facing roof lights must be obscure glazed and non-opening below 1.7m from the floor
- 3No volume is added to the roof space, so Class B volume limits do not apply
- 4The conversion itself is an internal alteration and does not need planning permission
Size and Dimension Limits
- Roof lights must not protrude more than 150mm from the roof plane
- No volume increase, so no specific volume limits
When Permitted Development Does Not Apply
- In conservation areas, roof lights may be restricted on principal or highway-facing elevations
- Listed building consent needed for listed buildings
- The structural capacity of the existing roof must support habitable use
What About Building Regulations?
Building regulations approval is likely required
Building Regulations approval is required even without a dormer. Covers structural load capacity of floor joists and roof structure, fire safety (escape windows, fire doors, protected stairway), staircase design and headroom, thermal insulation, sound insulation, ventilation, and electrical work.
Building regulations are separate from planning permission. Even if your project is permitted development, you may still need building regulations approval. Contact Westminster building control or use an approved inspector.
How to Apply in Westminster
If you need planning permission for your loft conversion with roof lights only, you can apply through Westminster's planning department or via the national Planning Portal.
If your project is permitted development and you want written confirmation, you can apply for a Lawful Development Certificate (LDC) from Westminster. This provides proof that your project does not need planning permission, which can be helpful when selling your property.
What Happens If I Build Without Permission?
While planning enforcement is unlikely for roof-light-only conversions (as they are almost always PD), a lack of Building Regulations sign-off is a serious problem. Without a completion certificate, you may struggle to sell the property or obtain a mortgage on it.
Frequently Asked Questions
Do I need planning permission for a loft conversion with roof lights only in Westminster?
Does a loft conversion with roof lights only in Westminster need building regulations?
How do I apply for planning permission in Westminster?
How long does planning permission take in Westminster?
What percentage of planning applications does Westminster approve?
Find a Loft Conversion Specialist in Westminster
Browse local loft conversion specialists on Tradesfolk. Read reviews, compare quotes, and hire with confidence. 100% free for homeowners, always.